Polyester extra-black yarn and preparation method thereof

Abstract

The invention discloses terylene extra-black yarn and a preparation method thereof. The polyester extra-black yarn is prepared from polyester through a spinning process, and the polyester is obtained by esterification and condensation polymerization of terephthalic acid, imidazole-4, 5-dicarboxylic acid and ethylene glycol according to the molar ratio of 1: (0.03-0.06): (1.1-1.2); black master batches are added into the polyester, the black master batches comprise 10-30wt% of modified carbon black, and the modified carbon black is prepared by carrying out esterification reaction on hydroxylated carbon black and a tetracarboxyl phenyl porphyrin metal complex according to the ratio of 100: (10-15). According to the application, an imidazole dicarboxylic acid structural unit is introduced into a polyester molecular chain and is matched with the application of the tetracarboxyl phenyl porphyrin metal complex modified carbon black, so that the phenomena of spinneret plate pollution and broken filaments caused by agglomeration and precipitation of the carbon black in the polyester extra-black yarn spinning process are remarkably relieved.

Description

Technical Field

[0001] The present application relates to the field of chemical fiber production, and in particular to a polyester special black yarn and a preparation method thereof. Background Art

[0002] As a high-performance specialty fiber, polyester black yarn has important application value in high-end clothing fabrics, automotive interiors, military camouflage materials and other fields due to its extreme blackness, excellent color fastness and uniform color performance. To meet the market's stringent requirements for deep black color, traditional production processes usually require the addition of a high proportion of black masterbatch to the polyester melt. These masterbatches use carbon black as the main coloring ingredient. However, as an inorganic pigment, carbon black has poor compatibility with the polyester matrix, resulting in its easy agglomeration during the melt blending process. This uneven dispersion not only directly reduces the mechanical properties of the fiber, but also causes some carbon black particles to migrate to the melt surface due to intensified thermal motion during the subsequent high-temperature spinning stage, and continue to precipitate and deposit at the outlet of the spinneret micropores.

[0003] Spinneret contamination triggers a multi-factor chain reaction: First, carbon black deposits gradually clog the spinnerets, causing fluctuations in single-filament fineness and uneven yarn length. Second, surface-enriched carbon black increases the surface energy of the nascent fibers, making it difficult for the spinning oil to evenly wet the fiber surface. The discontinuity of the oil film significantly increases the dynamic friction coefficient between the fiber and the yarn guide, subjecting the fiber to abnormal frictional stress during high-speed winding. These negative factors ultimately manifest as frequent filament breakage and breakage during production, severely hindering stable product production. Summary of the Invention

[0004] In order to alleviate the spinneret contamination and yarn breakage caused by carbon black agglomeration and precipitation during the spinning process of polyester special black yarn, the present application provides a polyester special black yarn and a preparation method thereof.

[0005] In the first aspect, the present application provides a polyester special black yarn, which is made from polyester through a spinning process, wherein the polyester is obtained by esterification and polycondensation reaction of terephthalic acid, imidazole-4,5-dicarboxylic acid, and ethylene glycol in a molar ratio of 1:0.03~0.06:1.1~1.2; a black masterbatch is added to the polyester, and the black masterbatch contains 10~30wt% of modified carbon black, and the modified carbon black is obtained by esterification reaction of hydroxylated carbon black and tetracarboxyphenylporphyrin metal complex in a ratio of 100:10~15.

[0006] In any of the above technical solutions, the black masterbatch accounts for 5 to 8% of the mass of the polyester.

[0007] In any of the above technical solutions, the tetracarboxyphenylporphyrin metal complex is any one or more of tetracarboxyphenylporphyrin copper, tetracarboxyphenylporphyrin zinc, tetracarboxyphenylporphyrin iron, and tetracarboxyphenylporphyrin nickel.

[0008] In any of the above technical solutions, the tetracarboxyphenylporphyrin metal complex is any one or more of tetracarboxyphenylporphyrin copper, tetracarboxyphenylporphyrin zinc, tetracarboxyphenylporphyrin iron, and tetracarboxyphenylporphyrin nickel.

[0009] In any of the above technical solutions, the preparation method of the modified carbon black is: adding hydroxylated carbon black to a tetracarboxyphenylporphyrin metal complex solution, mixing evenly, adding a catalyst in an amount of 5 to 10% by mass of the tetracarboxyphenylporphyrin metal complex, heating to 80 to 120° C., and reacting for 5 to 8 hours to obtain the modified carbon black.

[0010] In any of the above technical solutions, the catalyst used in the preparation of modified carbon black is p-toluenesulfonic acid.

[0011] In any of the above technical solutions, the black masterbatch is prepared by melting and blending polyester chips with modified carbon black, followed by extrusion, pelletizing, water cooling, and drying.

[0012] In any of the above technical solutions, the hydroxylation is achieved by chemical oxidation, such as treatment with concentrated sulfuric acid or hydrogen peroxide.

[0013] In any of the above technical solutions, the preparation method of the polyester is as follows: Esterification: Prepare terephthalic acid, imidazole-4,5-dicarboxylic acid and ethylene glycol into a slurry, add a catalyst and mix well, then pressurize in a nitrogen atmosphere to carry out esterification reaction to an absolute pressure of 0.2-0.3 MPa. The esterification reaction temperature is 230-250°C, and the reaction is carried out for 1-2 hours until the conversion rate reaches 80%-90%. The temperature is raised to 250-260°C, the pressure is reduced by 0.05-0.1 MPa, and the reaction is carried out for 1-1.5 hours. The reaction is terminated when the conversion rate reaches above 95%. Polycondensation: Add the catalyst to the esterification product, mix evenly, then raise the temperature to 260-270°C, reduce the pressure to 1-5 kPa, and react in a low vacuum for 1-2 hours; raise the temperature to 275-285°C, reduce the pressure to 50-80 Pa, and react in a high vacuum for 2-4 hours.

[0014] In any of the above technical solutions, terephthalic acid is preferably purified terephthalic acid; and the catalyst added to the esterification product is an antimony-based catalyst and / or a titanium-based catalyst.

[0015] Exemplarily, the antimony-based catalyst is antimony trioxide.

[0016] For example, the titanium catalyst is tetrabutyl titanate This application uses a tetracarboxyphenylporphyrin metal complex to modify the surface of carbon black. The carboxyl groups in the complex undergo an esterification reaction with the hydroxyl groups on the surface of the hydroxylated carbon black to form a stable chemical bond. At the same time, its large planar conjugated structure strengthens the binding force with the carbon black surface through π-π stacking, significantly inhibiting the agglomeration tendency of the carbon black particles. More importantly, the imidazole-4,5-dicarboxylic acid monomer is introduced into the polyester molecular chain. The imidazole group in its molecular structure is rich in lone pair electrons and can coordinate with the central ion of the porphyrin metal complex loaded on the surface of the modified carbon black, thus establishing a chemical connection between the polyester matrix and the carbon black. It effectively blocks the migration of carbon black to the melt surface during high-temperature spinning, thereby significantly reducing the precipitation and deposition of carbon black on the spinneret and fiber surface. The reduction in spinneret contamination directly improves spinning stability and increases yarn uniformity. At the same time, the fiber surface is evenly wetted with the oil, the frictional resistance is reduced, and the phenomenon of broken yarn ends is effectively reduced.

[0017] In any of the above technical solutions, a lubricating agent is added to the polyester at a mass ratio of 1 to 2% of the polyester, and the lubricating agent is prepared by esterification and polycondensation of terephthalic acid, hydroxystearic acid and ethylene glycol at a molar ratio of 1:0.1 to 0.2:1.0 to 1.1.

[0018] In any of the above technical solutions, the intrinsic viscosity of the lubricating agent is 0.15 to 0.25 dL / g.

[0019] In any of the above technical solutions, the preparation method of the lubricating agent is as follows: Esterification: Terephthalic acid, hydroxystearic acid and ethylene glycol are prepared into a slurry and the esterification reaction is carried out under nitrogen atmosphere and normal pressure. The esterification reaction temperature is 190-210°C and the reaction time is 2-3 hours. The reaction is terminated when the conversion rate reaches more than 95%. Polycondensation: Add the catalyst to the esterification product, mix evenly, raise the temperature to 210-230°C, reduce the pressure to 50-100 Pa, and react in vacuum for 2-3 hours to obtain the product.

[0020] In any of the above technical solutions, the catalyst added in the polycondensation step is an antimony-based catalyst and / or a titanium-based catalyst.

[0021] In any of the above technical solutions, the hydroxystearic acid is 10-hydroxystearic acid or 12-hydroxystearic acid.

[0022] A high content of carbon black will also deteriorate the melt fluidity, aggravate the phenomenon of carbon black precipitation and hairy yarn breakage, and deteriorate the mechanical properties and yarn uniformity of the special black yarn. The lubricating auxiliary agent of the present application can effectively improve the melt fluidity of polyester and reduce the above-mentioned production defects. Specifically, the auxiliary agent is based on terephthalic acid-hydroxystearic acid-ethylene glycol copolymer. The long alkyl chain of stearic acid in its molecular chain provides external lubrication to reduce the friction between the melt and the equipment wall, while the terephthalic acid unit forms a co-crystallization with the polyester matrix to enhance the internal lubrication effect. It should be noted that the intrinsic viscosity of the copolymer should be controlled in the range of 0.15-0.25dL / g.

[0023] Furthermore, traditional lubricants are prone to migration due to their compatibility. This migration can lead to accumulation on the inner wall of the spinning cup or on the surface of the metal sand, forming an oil film barrier. This weakens the filtration of impurities such as carbon black aggregates in the melt, exacerbating production problems such as spinneret contamination and yarn breakage. Because this additive is significantly more compatible with polyester than conventional internal and external lubricants like paraffin wax, it effectively inhibits the lubricant's tendency to migrate to the melt surface, maintaining a clean sand cup, improving impurity retention efficiency, and further reducing the risk of yarn breakage.

[0024] In the second aspect, the present application provides a method for preparing polyester special black silk. According to any raw material ratio of the polyester special black silk, terephthalic acid, imidazole-4,5-dicarboxylic acid, and ethylene glycol are subjected to esterification and polycondensation reaction to obtain a polyester melt. Black masterbatch and other additives are added to the polyester melt through an online addition system, and the polyester special black silk is obtained by melt direct spinning.

[0025] In any of the above technical solutions, the polyester special black yarn can be any one of POY yarn, FDY yarn or ITY yarn.

[0026] In summary, this application has the following beneficial effects: This application first introduces imidazole dicarboxylic acid structural units into the polyester molecular chain, imparting coordination capabilities between the matrix and carbon black. Secondly, the carbon black is modified with a tetracarboxyphenylporphyrin metal complex to establish a chemical connection between the carbon black and the polyester matrix, essentially inhibiting agglomeration and surface precipitation. Furthermore, a lubricating agent that balances fluidity and compatibility is used to ensure melt filtration efficiency. The synergistic effect of these three factors extends the continuous operating time of the spinneret, significantly reduces the yarn breakage rate, and improves the uniformity of the polyester yarn. DETAILED DESCRIPTION Preparation Example

[0027] Preparation Example 1-1, black masterbatch, is prepared as follows: 100g of carbon black was added to 1.5L of concentrated sulfuric acid (98wt%) and stirred at 300rpm / 85°C for 2 hours. After the reaction, the mixture was washed with deionized water until neutral and then dried in a vacuum oven at 80°C for 12 hours to obtain hydroxylated carbon black.

[0028] Take 100 g of hydroxylated carbon black into a solution of 13 g of copper tetra-carboxyphenyl porphyrin in N-methylpyrrolidone (concentration 10 wt%) and ultrasonic dispersion for 30 minutes. Add 1.3 g of p-toluenesulfonic acid and react at a constant temperature of 100°C for 6.5 hours under nitrogen protection. After the reaction solution is cooled to 60°C, centrifugal separation is performed, and the solid is washed with ethanol and acetone three times in turn, and then vacuum dried at 80°C for 12 hours to obtain the modified carbon black.

[0029] Put 260 g of polyester chips (intrinsic viscosity 0.65 dL / g, weight average molecular weight 25000 g / mol) and 40 g of the above modified carbon black into a high-speed mixer and pre-mix at 800 rpm for 10 minutes. The mixture is melt blended by a twin-screw extruder (L / D = 40, temperature zoning: I zone 260°C / II zone 275°C / III zone 280°C / IV zone 275°C), with a screw speed of 200 rpm and vacuum devolatilization (-0.095 MPa). The melt is cooled by a water tank and then pelletized (particle size 2 x 3 mm), and dried at 50°C for 4 hours to obtain black masterbatch.

[0030] Preparation Example 1-2, black masterbatch, is prepared as follows: Put 100 g of carbon black into 1.2 L of concentrated sulfuric acid (98 wt%), and stir at 300 rpm / 85°C for 3 hours. After the reaction is completed, wash with deionized water until neutral, and then treat in a vacuum drying oven at 70°C for 15 hours to obtain hydroxylated carbon black.

[0031] Take 100 g of hydroxylated carbon black into a solution of 10 g of zinc tetra-carboxyphenyl porphyrin in N-methylpyrrolidone (concentration 8 wt%) and ultrasonic dispersion for 30 minutes. Add 1.0 g of p-toluenesulfonic acid and react at a constant temperature of 80°C for 8 hours under nitrogen protection. After the reaction solution is cooled to 50°C, centrifugal separation is performed, and the solid is washed with ethanol and acetone three times in turn, and then vacuum dried at 90°C for 10 hours to obtain the modified carbon black.

[0032] Put 200 g of polyester chips (intrinsic viscosity 0.65 dL / g, weight average molecular weight 25000 g / mol) and 30 g of the above modified carbon black into a high-speed mixer and pre-mix at 800 rpm for 10 minutes. The mixture is melt blended by a twin-screw extruder (L / D = 40, temperature zoning: I zone 270°C / II zone 280°C / III zone 285°C / IV zone 275°C), with a screw speed of 200 rpm and vacuum devolatilization (-0.09 MPa). The melt is cooled by a water tank and then pelletized (particle size 2 x 3 mm), and dried at 45°C for 4 hours to obtain black masterbatch.

[0033] Preparation Example 1-3, black masterbatch, is prepared as follows: 100g of carbon black was added to 1.8L of concentrated sulfuric acid (98wt%) and stirred at 300rpm / 85°C for 3 hours. After the reaction, the mixture was washed with deionized water until neutral and then dried in a vacuum drying oven at 80°C for 12 hours to obtain hydroxylated carbon black.

[0034] 100g of hydroxylated carbon black was added to a solution of 15g of nickel tetracarboxyphenylporphyrin in N-methylpyrrolidone (8wt%) and ultrasonically dispersed for 30 minutes. 1.5g of p-toluenesulfonic acid was added, and the mixture was kept at 120°C under nitrogen for 5 hours. The reaction solution was cooled to 60°C and centrifuged. The solid was washed three times with ethanol and three times with acetone, and then dried in a vacuum at 80°C for 12 hours to obtain the modified carbon black.

[0035] 150g of polyester chips (intrinsic viscosity 0.65dL / g, weight-average molecular weight 25,000g / mol) and 50g of the modified carbon black were premixed in a high-speed mixer at 500rpm for 20 minutes. The mixture was melt-blended in a twin-screw extruder (L / D = 40, temperature zones: Zone I 280°C / Zone II 285°C / Zone III 290°C / Zone IV 285°C) at a screw speed of 300rpm and vacuum devolatilization (-0.1MPa). The melt was cooled in a water trough, pelletized (2x3mm), and dried at 55°C for 4 hours to produce a black masterbatch.

[0036] Preparation Example 1-4, modified carbon black, differs from Preparation Example 1-1 in that tetracarboxyphenylporphyrin copper is replaced by an equal amount of phenyltrimethoxysilane.

[0037] Preparation Example 2-1, a lubricating agent, is prepared according to the following steps: Esterification: Add 1000g of terephthalic acid, 218g of 12-hydroxystearic acid, and 759g of ethylene glycol to a reactor to form a slurry. After purging with nitrogen, replace the air. Raise the temperature to 200°C at 2°C / min. React at atmospheric pressure with mechanical stirring (120 rpm) for 2.5 hours. Esterification conversion, as monitored by distilled water, should be >95%.

[0038] Polycondensation: Add 1.5 g of tetrabutyl titanate to the esterification product. Reduce the system pressure to 75 Pa at a rate of 0.5 kPa / min while simultaneously raising the temperature to 220°C. Monitor the melt viscosity using an online viscometer. Stop the reaction when the intrinsic viscosity reaches 0.20 dL / g. Discharge the product under nitrogen pressure, cool with water, pelletize, and dry.

[0039] Preparation Example 2-2, a lubricating agent, is prepared according to the following steps: Esterification: Add 1000g of terephthalic acid, 145g of 10-hydroxystearic acid, and 690g of ethylene glycol to a reactor to form a slurry. After purging with nitrogen, replace the air. Raise the temperature to 190°C at a rate of 2°C / min. React at atmospheric pressure with mechanical stirring (120 rpm) for 3 hours. Esterification conversion, as monitored by the amount of distilled water, should be >95%.

[0040] Polycondensation: Add 1.0g of antimony trioxide (dissolved in 10g of ethylene glycol) to the esterification product. Reduce the system pressure to 90Pa at a rate of 0.5kPa / min while simultaneously raising the temperature to 210°C. Monitor the melt viscosity using an online viscometer. Stop the reaction when the intrinsic viscosity reaches 0.15dL / g. Discharge the product under nitrogen pressure, cool with water, pelletize, and dry.

[0041] Preparation Example 2-3, a lubricating agent, was prepared according to the following steps: Esterification: Add 1000g of terephthalic acid, 290g of 12-hydroxystearic acid, and 828g of ethylene glycol to a reactor to form a slurry. After purging with nitrogen, replace the air. Raise the temperature to 210°C at 3°C / min. React at atmospheric pressure with mechanical stirring (120 rpm) for 2 hours. Esterification conversion, as monitored by distilled water, should be >95%.

[0042] Polycondensation: Add 2g of tetrabutyl titanate (dissolved in 10g of ethylene glycol) to the esterification product. Reduce the system pressure to 50 Pa at a rate of 0.5kPa / min while simultaneously raising the temperature to 230°C. Monitor the melt viscosity using an online viscometer. Stop the reaction when the intrinsic viscosity reaches 0.25dL / g. Discharge the product under nitrogen pressure, cool with water, pelletize, and dry.

[0043] Preparation Example 2-4, a lubricating agent, was prepared according to the following steps: Esterification: Add 1000g of terephthalic acid, 218g of 12-hydroxystearic acid, and 759g of ethylene glycol to a reactor to form a slurry. After purging with nitrogen, replace the air. Raise the temperature to 200°C at 2°C / min. React at atmospheric pressure with mechanical stirring (120 rpm) for 2.5 hours. Esterification conversion, as monitored by distilled water, should be >95%.

[0044] Polycondensation: Add 1.0 g of tetrabutyl titanate to the esterification product. Reduce the system pressure to 50 Pa at a rate of 0.2 kPa / min while simultaneously raising the temperature to 210°C. Monitor the melt viscosity using an online viscometer. Stop the reaction when the intrinsic viscosity reaches 0.35 dL / g. Discharge the product under nitrogen pressure, cool with water, pelletize, and dry.

[0045] Preparation Example 2-5, a lubricating agent, differs from Preparation Example 1 in that 12-hydroxystearic acid is replaced with an equal amount of terephthalic acid. The preparation steps are as follows: Esterification: Add 1218g of terephthalic acid and 759g of ethylene glycol to a reactor to form a slurry. Replace the air with nitrogen. Raise the temperature to 200°C at 2°C / min. React at atmospheric pressure with mechanical stirring (120 rpm) for 2.5 hours. Esterification conversion, as monitored by distilled water, should be >95%.

[0046] Polycondensation: Add 1.5 g of tetrabutyl titanate to the esterified product. Reduce the system pressure to 605 Pa at a rate of 0.3 kPa / min while simultaneously raising the temperature to 210°C. Monitor the melt viscosity using an online viscometer. Stop the reaction when the intrinsic viscosity reaches 0.20 dL / g. Discharge the product under nitrogen pressure, cool with water, pelletize, and dry. Example

[0047] Example 1: A polyester special black yarn is prepared according to the following steps: Polyester Synthesis: 1000g of terephthalic acid, 36.2g of imidazole-4,5-dicarboxylic acid, and 496g of ethylene glycol were prepared into a slurry. Esterification was carried out at 235°C for 1.5 hours under nitrogen pressure (absolute pressure 0.25 MPa) to a conversion of 85%. The temperature was raised to 255°C, the pressure was reduced to 0.2 MPa, and the reaction was continued for 1.2 hours until the conversion reached >95%. 0.65g of tetrabutyl titanate was added to the esterified product. The reaction was carried out at 265°C / 3 kPa under low vacuum for 1.5 hours, followed by high vacuum at 280°C / 65 Pa for 3 hours to obtain a polyester melt with an intrinsic viscosity of 0.68 dL / g.

[0048] Online addition: The polyester melt is transported to the static mixer through the melt pipe, and 65 g of the black masterbatch of Preparation Example 1-1 (added at 6.5% of the mass of the polyester melt) and 15 g of the lubricating agent of Preparation Example 2-1 (added at 1.5% of the mass of the polyester melt) are simultaneously injected through the online addition system.

[0049] Melt extrusion: The mixed melt is homogenized by a screw extruder (L / D=36, temperature 285°C) and output to the spinning assembly (metal sand specification 20μm) by a metering pump.

[0050] Cooling molding: The melt is extruded from the spinneret and cooled by ring blowing (air pressure 20±2Pa, air temperature 20.5±1℃).

[0051] Oiling and drawing: After the fibers are bundled, they pass through oil rollers (oil concentration 60%, oiling rate 0.7%) and five-roll hot drawing (the temperature of the first, second and third rollers is 82-85°C, the temperature of the fourth and fifth rollers is 123±1°C, and the total drawing ratio is 2.3).

[0052] Winding and shaping: The shaping hot roller is treated at 180℃, the main network pressure is 0.25MPa, and the winding speed is 4500m / min to produce 230dtex / 144F polyester special black yarn.

[0053] Example 2: A polyester special black yarn is prepared according to the following steps: Polyester Synthesis: 1000g of terephthalic acid, 24.1g of imidazole-4,5-dicarboxylic acid, and 435g of ethylene glycol were prepared into a slurry. Esterification was carried out at 230°C for 2 hours under nitrogen pressure (absolute pressure 0.25 MPa) to a conversion of 85%. The temperature was raised to 250°C, the pressure was reduced to 0.2 MPa, and the reaction was continued for 1.5 hours until the conversion reached >95%. 0.5g of tetrabutyl titanate was added to the esterified product, and the reaction was carried out at 260°C / 5 kPa under low vacuum for 2 hours, followed by high vacuum at 275°C / 80 Pa for 4 hours to obtain a polyester melt with an intrinsic viscosity of 0.65 dL / g.

[0054] Online addition: The polyester melt is transported to the static mixer through the melt pipe, and 52 g of the black masterbatch of Preparation Example 1-2 (added at 5.2% of the mass of the polyester melt) and 10 g of the lubricating agent of Preparation Example 2-2 (added at 1.0% of the mass of the polyester melt) are simultaneously injected through the online addition system.

[0055] Melt extrusion: The mixed melt is homogenized by a screw extruder (L / D=36, temperature 280°C) and output to the spinning assembly (metal sand specification 20μm) by a metering pump.

[0056] Cooling molding: The melt is extruded from the spinneret and cooled by ring blowing (air pressure 20±2Pa, air temperature 20.5±1℃).

[0057] Oiling and drawing: After the fibers are bundled, they pass through oil rollers (oil concentration 60%, oiling rate 0.6%) and five-roll hot drawing (the temperature of the first, second and third rollers is 82-85°C, the temperature of the fourth and fifth rollers is 123±1°C, and the total drawing ratio is 2.1).

[0058] Winding and shaping: The shaping hot roller is treated at 170℃, the main network pressure is 0.3MPa, and the winding speed is 4200m / min to produce 230dtex / 144F polyester special black yarn.

[0059] Example 3, a polyester special black silk, is prepared according to the following steps: Polyester Synthesis: Prepare a slurry of 1000g terephthalic acid, 48.3g imidazole-4,5-dicarboxylic acid, and 538g ethylene glycol. Esterify at 240°C for 1.5 hours under nitrogen pressure (absolute pressure 0.2 MPa) to a conversion of 85%. Raise the temperature to 260°C, reduce the pressure to 0.15 MPa, and continue the reaction for 1 hour until the conversion exceeds 95%. Add 1.0g tetrabutyl titanate to the esterified product, and react at 270°C / 1 kPa under low vacuum for 1 hour, followed by high vacuum at 285°C / 50 Pa for 2.5 hours to obtain a polyester melt with an intrinsic viscosity of 0.70 dL / g.

[0060] Online addition: The polyester melt is transported to the static mixer through the melt pipe, and 78 g of the black masterbatch of Preparation Example 1-3 (added at 7.8% of the mass of the polyester melt) and 20 g of the lubricating agent of Preparation Example 2-3 (added at 2.0% of the mass of the polyester melt) are simultaneously injected through the online addition system.

[0061] Melt extrusion: The mixed melt is homogenized by a screw extruder (L / D=36, temperature 290°C) and output to the spinning assembly (metal sand specification 20μm) by a metering pump.

[0062] Cooling molding: The melt is extruded from the spinneret and cooled by ring blowing (air pressure 20±2Pa, air temperature 20.5±1℃).

[0063] Oiling and drawing: After the fibers are bundled, they pass through oil rollers (oil concentration 60%, oiling rate 0.8%) and are hot drawn by five rollers (the temperature of rollers 1, 2 and 3 is 82-85°C, the temperature of rollers 4 and 5 is 123±1°C, and the total drawing ratio is 2.3).

[0064] Winding and shaping: The shaping hot roller is treated at 190℃, the main network pressure is 0.3MPa, and the winding speed is 4800m / min to produce 230dtex / 144F polyester special black yarn.

[0065] Example 4, a polyester special black silk, is different from Example 1 in that the lubricating agent of Preparation Example 2-1 is replaced by an equal amount of the lubricating agent of Preparation Example 2-4.

[0066] Example 5, a polyester special black silk, is different from Example 1 in that the lubricating agent of Preparation Example 2-1 is replaced by an equal amount of the lubricating agent of Preparation Example 2-5.

[0067] Example 6, a polyester special black silk, differs from Example 1 in that the lubricating agent in Preparation Example 2-1 is replaced by an equal amount of pentaerythritol stearate. Comparative Example

[0068] Comparative Example 1 is a polyester special black yarn, which differs from Example 1 in that the black masterbatch of Preparation Example 1-1 is replaced by an equal amount of the black masterbatch of Preparation Example 1-4.

[0069] Comparative Example 2 is a polyester special black yarn, which differs from Example 1 in that, in the polyester synthesis step, an equal amount of terephthalic acid is used to replace imidazole-4,5-dicarboxylic acid.

[0070] Comparative Example 3, a polyester special black silk, differs from Comparative Example 1 in that, in the polyester synthesis step, an equal amount of terephthalic acid is used to replace imidazole-4,5-dicarboxylic acid. Performance testing

[0071] Experiment 1: Statistics of broken ends of wool During the production process, the number of hair strands (times / day•108 pieces) and the number of broken ends (times / day•108 pieces) within 5 working days were counted, and the results were taken as integer averages.

[0072] Test 2: Spinneret deposit detection After each group of examples and comparative examples had been spun continuously for 24 hours, the spinneret was immediately disassembled, and the sediment on the spinneret was cleaned and collected, and its mass (unit: mg) was weighed.

[0073] Test 3: Strip evenness test With reference to the provisions of FZ / T 54118-2019 "High Shrinkage Polyester Drawn Yarn / Polyester Pre-Oriented Yarn Blended Yarn", the linear density variation coefficient CV (%) of the polyester special black yarn obtained in the examples and comparative examples was tested to characterize its yarn uniformity.

[0074] Test 4: Breaking Strength Test With reference to the provisions of FZ / T 54118-2019 “High Shrinkage Polyester Drawn Yarn / Polyester Pre-Oriented Yarn Blended Yarn”, the breaking strength (cN / dtex) of the polyester special black yarn obtained in the examples and comparative examples was measured.

[0075] Table 1. Performance test results

[0076] Analysis of test results: Example 4 exhibited poor performance in terms of yarn uniformity (linear density coefficient of variation) and carbon black precipitation suppression. This may be due to the use of a lubricating agent with an intrinsic viscosity greater than 0.25 dL / g, which reduced its internal lubrication of the polyester melt and increased melt flow resistance, resulting in uneven flow rates across spinnerets and large fluctuations in linear density. This also increased yarn defects, reduced mechanical properties, and increased production defects. Similarly, Example 5, due to the lack of long-chain alkyl grafting, exhibited reduced internal and external lubrication, resulting in decreased yarn uniformity, increased spinneret deposits, and increased lint breakage. Example 6, due to poor compatibility with the polyester melt, increased migration and weakened impurity filtration, leading to increased production defects.

[0077] The spinneret deposit content, lint, and broken yarns in Comparative Examples 1 to 3 all showed a significant increase, with similar increases. This may be due to the lack of imidazole groups in the polyester matrix or the lack of a tetracarboxyphenylporphyrin metal complex on the carbon black surface, preventing effective chemical bonding between the polyester agent and the carbon black. This significantly reduced the carbon black's ability to resist migration and precipitation, leading to a sharp increase in the aforementioned production defects.

[0078] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A polyester special black yarn, characterized in that: The polyester is prepared by a spinning process, wherein the polyester is obtained by esterification and polycondensation of terephthalic acid, imidazole-4,5-dicarboxylic acid and ethylene glycol in a molar ratio of 1:0.03-0.06:1.1-1.2; a black masterbatch is added to the polyester, wherein the black masterbatch contains 10-30wt% of modified carbon black, and the modified carbon black is obtained by esterification of hydroxylated carbon black and a tetracarboxylphenylporphyrin metal complex in a molar ratio of 100:10-15.

2. The polyester special black yarn according to claim 1, characterized in that: The black masterbatch accounts for 5-8% of the mass of polyester.

3. The polyester special black yarn according to claim 1, characterized in that: The tetracarboxyphenylporphyrin metal complex is any one or more of tetracarboxyphenylporphyrin copper, tetracarboxyphenylporphyrin zinc, tetracarboxyphenylporphyrin iron, and tetracarboxyphenylporphyrin nickel.

4. The polyester special black yarn according to claim 3, characterized in that: The preparation method of the modified carbon black comprises the following steps: adding hydroxylated carbon black to a tetracarboxylphenylporphyrin metal complex solution, mixing well, adding a catalyst in an amount of 5 to 10% by mass of the tetracarboxylphenylporphyrin metal complex, heating to 80 to 120° C., and reacting for 5 to 8 hours to obtain the modified carbon black.

5. The polyester special black yarn according to claim 1, characterized in that: The preparation method of the polyester is as follows: Esterification: Prepare terephthalic acid, imidazole-4,5-dicarboxylic acid and ethylene glycol into a slurry, add a catalyst and mix well, then pressurize in a nitrogen atmosphere to carry out esterification reaction to an absolute pressure of 0.2-0.3 MPa. The esterification reaction temperature is 230-250°C, and the reaction is carried out for 1-2 hours until the conversion rate reaches 80%-90%. The temperature is raised to 250-260°C, the pressure is reduced by 0.05-0.1 MPa, and the reaction is carried out for 1-1.5 hours. The reaction is terminated when the conversion rate reaches above 95%. Polycondensation: Add the catalyst to the esterification product, mix evenly, then raise the temperature to 260-270°C, reduce the pressure to 1-5 kPa, and react in a low vacuum for 1-2 hours; raise the temperature to 275-285°C, reduce the pressure to 50-80 Pa, and react in a high vacuum for 2-4 hours.

6. The polyester special black yarn according to claim 1, characterized in that: The polyester is added with a lubricating auxiliary agent in an amount of 1 to 2% by mass of the polyester. The lubricating auxiliary agent is prepared by esterification and polycondensation of terephthalic acid, hydroxystearic acid and ethylene glycol in a molar ratio of 1:0.1 to 0.2:1.0 to 1.

1.

7. The polyester special black yarn according to claim 6, characterized in that: The intrinsic viscosity of the lubricating agent is 0.15 to 0.25 dL / g.

8. The polyester special black yarn according to claim 6, characterized in that: The preparation method of the lubricating agent is as follows: Esterification: Terephthalic acid, hydroxystearic acid and ethylene glycol are prepared into a slurry and the esterification reaction is carried out under nitrogen atmosphere and normal pressure. The esterification reaction temperature is 190-210°C and the reaction time is 2-3 hours. The reaction is terminated when the conversion rate reaches more than 95%. Polycondensation: Add the catalyst to the esterification product, mix evenly, raise the temperature to 210-230°C, reduce the pressure to 50-100 Pa, and react in vacuum for 2-3 hours to obtain the product.

9. The polyester special black yarn according to claim 1, characterized in that: The hydroxystearic acid is 10-hydroxystearic acid or 12-hydroxystearic acid.

10. A method for preparing polyester special black yarn, characterized in that: According to the raw material ratio of the polyester special black yarn according to any one of claims 1 to 9, terephthalic acid, imidazole-4,5-dicarboxylic acid and ethylene glycol are subjected to esterification and polycondensation to obtain a polyester melt, black masterbatch and other additives are added to the polyester melt through an online adding system, and the polyester special black yarn is obtained by melt direct spinning.

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